Every day, parents and teachers across this country tell young people to dream big, not to sell themselves short, and to prepare to go farther and higher than the previous generation. Corporations spend a lot of time, energy and money trying to get employees to get out of their comfort zones and think outside the box. So can someone explain to me why it's a bad thing when the president of the United States does it?

After President Barack Obama's speech to a joint session of Congress Tuesday night, several of my fellow political pundits cautioned the president not to have a large agenda. Don't seem "overly ambitious" was a buzz phrase of the evening. It was as if folks were channeling those who say, "Under-promise and over-perform."

Sorry, folks, but I don't get that kind of thinking. How can the leader of the Free World be overly ambitious? In these difficult moments, with an economy brought to its knees, why have we become a nation of low expectations?

That also irked me during the campaign. I never will forget the vice presidential debate and many of us discussing what then-Sen. Joe Biden and Gov. Sarah Palin should try to achieve. I finally got so sick and tired of what I was hearing that I blurted out: "Guys! This is the second-most important job in the world. I have higher expectations for my nieces, and they are in elementary school."

Frankly, I'm tired of presidents, members of Congress and everyday folk taking the path of least resistance. My pastor always says no day is promised, so if that's the case, why do we engage in this counterproductive lowering of expectations?

I have a theory that might explain it: We are afraid of failure.

When everyday people think of dreams and aspirations, it often is met by doubt. Politicians don't want to think big, because if they never get there, then they'll be accused of overselling and coming up short, or they'll have to back down from big announcements.

OK, fine, stuff happens. But we should be encouraging ambitious thinking.

As I listened to the president talk about education, health care and ending our dependence on foreign oil, I felt great. He talked about creating millions of jobs, getting credit flowing again, investing in our social needs, such as schools, and making "hard choices to bring our deficit down." And that doesn't even include his foreign policy goals, including defeating al-Qaida, making progress on Mideast peace, stopping nuclear proliferation and combating worldwide disease and poverty.

It was the same feeling I got when Presidents George H.W. Bush, Bill Clinton and George W. Bush addressed Congress. It's wonderful to hear a president offer us a blueprint for the future, and if we can meet it, cool. (That's my niece Ana's answer to everything that tickles her ears.)

Obama knows that a second term is not guaranteed. He has been given four years. It's his chance to show the American people that he is willing to roll up his sleeves and get to work. Too many folks say: "Slow down. You don't want to bite off more than you can chew." Nonsense.

Tuesday night, I compared the president's pronouncement to rapper Kanye West. When he was promoting his CD, the Chicago entertainer told a number of journalists that he wanted it to be better than Stevie Wonder's "Songs in the Key of Life." That was seen as sacrilegious because Wonder's album is considered one of the greatest in the history of music.

West's response? Even if I don't achieve that feat, it still will be as good as anything else out there now.

West was willing to set as his target one of the greatest because he wants to be great. So why shouldn't we encourage that for everyone? Why do we have to accept mediocrity from our political leaders? We've had enough of that.

No one knows whether Obama will be able to fulfill everything he outlined. Bill Clinton couldn't reform health care, and George W. Bush didn't remake Social Security.

But making the effort to shoot for the stars means you just might reach them. And if not? Well, you gave it your best shot and achieved as much as possible. Isn't that what we teach our children to do every day?

Roland S. Martin is an award-winning CNN contributor and the author of "Listening to the Spirit Within: 50 Perspectives on Faith."